Some considerations relative to the use of percussion instrument support racks will be discussed to facilitate an understanding of the relevant technology. Typically, a percussion instrument support rack (a type of item support rack) will include rails and legs that support the rails. The rails themselves, which may have in other descriptions been referred to as tiers, may serve as attachment sites and provide support for percussion instruments (whether directly in the case where the percussion instrument is attached directly to the rail, or indirectly in the case where a riser or other attachment structure is attached to the rail and a percussion instrument is attached to the riser). Sometimes it may be appropriate to position all instruments at substantially the same height, but more often tradition or practicality requires placement of several instruments at varying heights above the supporting base (e.g., a floor). Most specifically in the case of percussion instruments, it is traditional as well as practically desirable to position the instruments so that they collectively follow first a rising sweep from left to center left and then smoothly transition or arch at center to a falling sweep from center right to right, allowing the user to play ascending and descending percussion patterns with ease. Of course, the terms center, left and right are with respect to a user of the instruments (e.g., a drummer), where center could be essentially that position that the user would face in assuming a position in preparation to use all the instruments. Other preferred placements of instruments might call for a variation or even a reversal of this sweep of instruments or might require a more abrupt change from a rising to a falling rail axis.
Another desirable function or attribute or characteristic of multi-railed instrument stands that at least partially surround a player is the ability to be adjusted for radial distance from the user. Since the stand partially surrounds the user, merely moving the stand closer to or farther away from the user in a single direction will result in an off-center user position, which is often detrimental to good instrument access in other directions. Thus it may be important in some applications that the radius of the arc approximated by the rail array (as projected on a horizontal plane), or a portion of that arc, be adjustable. It should also be noted that the commonly practiced placement of larger percussion instruments on one side of the user and smaller instruments on the other side of the user might require that the rail array more closely approximate (again, in its projection onto a horizontal plane) a segment of a spiral of expanding radius in order to maintain a more constant distance between the user and the inner edge of the supported instruments. Such a use may require that the relative horizontal angle of an outer rail to its adjacent inner rail be different for the left outer rail than for the right outer rail.
In providing or establishing pivot axes for radial or spiral horizontal rail array adjustment, it is important to understand the effects of non-verticality of the pivot axes. If such a pivot axis is not vertical, an outer rail end, while being pivoted about this axis, does not move in a horizontal arc, and thus the height of at least a portion of it changes simultaneously as its angular position (relative to another rail attached to it, e.g.,) changes. Such pivoting may raise or lower any leg attached to the rail under adjustment (e.g., to the outer end of the rail). In cases where the total number of legs is greater than three, this height change will result in a detrimental condition of non-coplanarity of the several legs' lower ends (feet)—the legs will no longer all contact the floor and will require significant additional adjustments to bring all feet back into contact with the floor. Additionally, this height change and/or the secondary adjustments needed to compensate for it can result in unintentional vertical tilting of the rail array (e.g., tilting in towards or out from a drummer seated in the center of the array), which may require yet more adjustment to correct. For these and perhaps other reasons, it may be desirable to provide and maintain vertical pivot axes for the inner ends of outer rails.
Yet another desirable function of instrument support racks may be the directing of cables (e.g., powering or signal cables for electronic drums) through an interior space defined by (e.g., within) a rail, from one point on the rail to another, e.g., from an end of the rail to the other, or from one end of a rail to a termination point or a point of ingress or egress at an intermediate location along the rail or rail span (as but a few examples). In this way signal and/or power cables associated with supported instruments can be hidden from view for a portion of their length, improving the stand's appearance and reducing tangling and snagging of cables during use, transport or storage.
Where a hollow member (e.g., a tube) is used as a rail, it is of course possible to create holes or ports in the rail sidewall at both ends of the rail, through which cables can pass. However, this practice requires a costly secondary aperture operation (e.g., drilling) to be performed at each end of the rail, and may require the use of a costly junction box or grommet or baffle to make the holes visually acceptable and/or noninjurious to the cables. Further, it may reduce the length of the portion of the rail to which instruments can be attached. Additionally, by removing load-carrying material from the rail, holes in the rail sidewalls create stress risers, compromising the rail's mechanical structure at the very locations at which it may need to be strongest—the end joints.
One might also wish to consider the use of holes in the legs for passing cables out the end opening of one rail and into the end opening of the next rail without exiting the stand structure. But a little thought shows the difficulty this practice would create with respect to rail horizontal angle adjustment or collapse for transport or vertical rail end height adjustment, as any of these may cause a shearing action between the rail end and edges of the hole in the leg which could cause cables to be cut, damaged, or at least stressed. Further, once again a structural member, in this case the leg, would have its strength and stiffness compromised by a major interruption in its load-bearing structure.